### Defining a modular form from it's $q$-expansion coefficients

I have a certain modular form for $\Gamma(N)$ and weight $0$ which I know but just by it's $q$-expansion coefficients, and I want to compute the action of Hecke operators on this modular form. How do I define a modular form object from its q-expansion coefficients, so that I can use it as an input for M.hecke_operator?